1. Field of the Invention
The present invention relates to an arc spot welding torch for arc spot welding in which an operation switch of a holder activates the torch by pressing a nozzle of the welding torch onto a workpiece.
2. Description of the Related Art
Generally speaking, the target workpiece to be arc spot welded may have various shapes such as a narrow and complicated shape, vertical a wall in a box and the like. Arc spot welding torches for general use which are commercially available are made small in shape in order to meet various targets.
In the meanwhile, arc spot welding apparatuses as shown in FIG. 14 are on the market for building constructions such as deck plates of electric cars or architectural structures. The arc spot welding apparatus is comprised of a power source unit A for supplying electric power for welding, a wire feeder B for feeding electrode wire which is connected to the power source unit A by a control cable D, and an arc spot welding torch T' which is connected to the wire feeder B by a torch cable F.
Arc spot welding apparatuses as shown in FIG. 15 are also on the market. This type of arc spot welding apparatus further comprises one more wire feeder C to be arranged near the welding torch T' which is connected to the wire feeder B and the arc spot welding torch T' by an intermediate cable E and a torch cable F, respectively. This wire feeder C contributes to rise the feeding power of the electrode wire and, thereby, the working area can be widened.
As shown in FIG. 17, the welding torch used in the welding apparatus comprises a power supply element 4 for supplying electric power to a welding electrode, a baffle 11 having small apertures 111 for spouting shield gas and a nozzle 8' enclosing the welding electrode and the power supply element 4 at the tip end thereof. Upon welding, the nozzle 8' is abutted onto a target work and an arc is generated by supplying electric power between the welding electrode and the target work via the power supply element 4.
In the meanwhile, upon arc spot welding, it is necessary to make an upper metal plate, stick to a lower metal plate, namely a base metal by the upper metal plate with the nozzle since the upper metal plate is piled on the base metal and is melted to weld to the base metal.
As shown in FIGS. 14 and 15, since both welding torches T' used for the welding apparatus are relatively small by the reason mentioned above, the operator has to bend himself or his knees to operate the welding torch upon arc spot welding. Since a time necessary for arc spot welding one spot is a few seconds at the most, such an unstable posture as mentioned above may be considered to be acceptable. But a relatively heavy quota is assigned to the operator because of the shortness of welding time per one spot. In the operation of the welding apparatus, the operator will walk from one spot to the next spot to be welded and bend himself for actual arc spot welding in a short time and, therefore, becomes very fatigued in order to finish his quota assigned to him.
Further, it becomes difficult to press the upper plate onto the base metal plate with a reasonable force in the bent posture, especially when the operator may become fatigued. This may invite dangerous weld defects which are difficult to find in appearance after the welding.
In the welding operation for welding a deck plate P, as shown in FIGS. 15 and 16, the operator moves along a groove of the deck plate P, namely in X direction, to weld individual spots while putting the wire feeder C of the torch side in another groove. The wire feeder is moved along the groove by pulling the torch cable F. When the welding operation with respect to one groove is finished, the operator moves to the next groove to be welded in Y direction. If it becomes necessary to move the wire feeder C for the next welding operation, the operator has to bring it up by grasping the handle CH thereof in order to move it to a suitable groove on the deck plate. However, the operator is apt to pull the torch cable F in order to move the wire feeder C forcibly. This invites falling of the wire feeder C and/or cutting of the torch cable F.
On the other hand, so called sputters being molten metal of several hundred degrees (.degree.C.) are generated during the arc spot welding operation and almost of them adhere to the inner surface of the nozzle N', as shown in FIG. 17, since it is pressed onto the upper plate. If the amount of sputters adhered increases, various inconveniences such as turbulence of the shield gas flow, and electrical short circuit between the nozzle N' and the power supply element 4 may be caused. In order to avoid these inconveniences, it becomes necessary to remove adhered sputters on the way of the welding operation. However, the removing operation of the adhered sputters is laborious because it has to be done after detaching the nozzle N'. Further, it is impossible to observe a state of adhesion of the sputter from the outside and, thereby, an opportunity for removing the adhered sputters is apt to lose. This causes various inconveniences mentioned above. In order to decrease the adhesion amount of sputters, there has been known a method wherein the tip end portion of the welding torch is immersed beforehand into a liquid for preventing sputters from adhering. However, if this method is performed as it is, the liquid is prevented from going inside of the nozzle N' by the air remaining in the nozzle N' and, thereby, it is not spread inside of the nozzle sufficiently. Thus, it fails to prevent sputters from adhering. If the nozzle N' and elements 4 and 11 of the tip and of the welding torch T' are immersed into the liquid after detaching the nozzle from the welding torch, it becomes possible to prevent sputters from adhering satisfactorily but the immersing operation becomes laborious since the nozzle has to be detached from the welding torch at that time.